This Instagram Star Is the World&#039;s Most Influential Fitness Trainer

#BBG. #KaylasArmy. If you don’t know these hashtags already, you’re about to. They make regular appearances in the Instagram world on inspiring body transformation photos. And what do they mean? #BBG stands for Bikini Body Guide ($70), a PDF containing 12 weeks of body-changing workouts created by Kayla Itsines (of #KaylasArmy). The Australian personal trainer with a whopping 3.3 million followers on Instagram says her success (and social media celebrity) is somewhat accidental. “I started my Instagram as a personal way to keep track of all my client transformations and home workout videos in one place,” Itsines tells Well+Good. But what she did was start an army of fitness-loving fans. Keep reading to find out how Itsine became the most influential trainer!

As soon as the Instagram community got a glimpse at Itsine’s remarkable client progress photos, users wanted in on the action. “I started getting questions from women all around the world asking how I was training them,” Itsines says. “I started receiving so many emails, I thought, ‘Maybe I could help people all over the globe.’” And so a fitness revolution was born. Itsines and her business partner spent almost a year creating the no-nonsense regimen. The 28-minute workouts are straightforward and challenging (think mountain climbers and jump squats). They’re high-intensity workouts you can do anywhere. Most of the workouts you can do without equipment (a few require hand weights), but if you download the guides or follow Itsine on Instagram, you’ll soon learn she’s a fan of the foam roller (try LuxFit’s Premium High Density Foam Rollers, $8-$28).

The BBG program is only the beginning for Itsines. Learn more about Itsines, the program, and what’s next on Well+Good.

Want to see what all the hype is about? Scroll down to see some of most impressive (and inspiring) transformations Itsine has posted!